Generation of a highly efficient and tissue-specific tryptophan hydroxylase 1 knockout mouse model

Area of Science:

• Biochemistry
• Genetics
• Physiology

Background:

• Serotonin (5-hydroxytryptamine [5-HT]) has recognized tissue-autonomous functions in peripheral organs.
• Previous mouse models using Tph1^tm1Kry alleles did not achieve complete 5-HT ablation due to a truncated TPH1 form.
• Residual 5-HT production in Tph1^tm1Kry KO mice is linked to a truncated TPH1 containing the catalytic domain.

Purpose of the Study:

• To generate a Tph1 null mouse model with a complete ablation of 5-HT production.
• To create an improved Tph1 floxed allele (Tph1^tm1c) targeting the catalytic domain of TPH1.
• To validate the efficacy of the new model in studying peripheral serotonin systems.

Main Methods:

• Generation of a new Tph1 floxed allele, Tph1^tm1c, targeting exons 5 and 6.
• Crossing Tph1^tm1c floxed mice with tissue-specific Cre driver lines (villin-Cre and insulin-Cre).
• Quantification of 5-HT production in specific tissues (intestine and β cells).

Main Results:

• The Tph1^tm1c allele targets exons encoding the catalytic domain of TPH1.
• Crossing with villin-Cre or insulin-Cre resulted in near-complete ablation of 5-HT production in the intestine and β cells, respectively.
• The new model effectively eliminates residual 5-HT production observed in previous models.

Conclusions:

• The developed Tph1^tm1c floxed mouse model provides a more accurate tool for studying peripheral serotonin.
• This model allows for precise investigation of serotonin's role in various peripheral tissues.
• It overcomes limitations of previous models in achieving complete 5-HT ablation.